Barium titanate and zirconate, as well as strontium titanate and zirconate are well-known electroceramic materials possessing useful properties such as ferroelectric or piezoelectric properties. Because of their properties certain of these materials have been employed as capacitors, voltage surge suppressors in computers, and as hydrostatic piezoresistive sensing materials. They are commonly employed in motors and as transducers in audio equipment, especially speaker components. These materials can also be used as refractories for high temperature applications, as pigments and in catalytic applications. In the past, the various available processes for making such materials involved a trade-off between production costs and purity. That is, one could either practice a reasonably economic process but produce a relatively impure or contaminated material or one could obtain a material of rather high purity by an expensive process. As an example, barium titanate can be manufactured from titania and barium carbonate by a simple heating process at elevated temperatures. Such a process is reasonably inexpensive but, unfortunately, the ultimate barium titanate material is not of the best quality from a purity point of view. Alternatively, a reasonably high purity material can be obtained by employing titanium tetrachloride as a starting material. Unfortunately, however, because of the rapid hydrolysis of titanium tetrachloride, this material needs to be processed in organic solvents. Organic solvents, of course, may not only create toxicity problems during production but are also more expensive than an aqueous system. Consequently, the use of TiCl.sub.4 results in a rather expensive process although a relatively high purity material is obtainable. Since TiCl.sub.4 is highly hydrolyzable it, consequently, cannot be cheaply and conveniently stored for prolonged periods of time. This, of course, has its adverse economic penalties. If a titanium compound, or intermediate, could be found and used which is not of such a high reactivity, it would be a financial benefit in the production of, for example, titanates.
Thus, it will be seen that there is a need in the art for a process for forming titanate and zirconate materials which does not involve the use of organic solvents and which would use water. There is likewise a need for a process which uses inexpensive, stable starting materials and in which the chemical intermediates are stable and easily storable.
In accordance with the present invention, the problems and the needs in the art are satisfied by providing a process for economically producing high purity materials. The process is practiced in an aqueous medium and thereby precludes the necessity for using organic solvents. It uses cheap, stable and readily available starting materials. Additionally, during the process, an intermediate is formed which can be stored for prolonged periods of time and which is not easily susceptible, unlike titanium tetrachloride, to rapid hydrolysis when in contact with humid air.